This is a prospective, open-label pharmacokinetic and safety study of multiple doses of IV and oral clindamycin in overweight and obese children ages 2 to 17 years of age. The total study duration is expected to be approximately 24 months; each subject will participate in the study for up to 18 days (screening day; treatment days 1-14 [may be as short as 2 days] followed by an observation period of 3 days post discontinuation of clindamycin therapy or after day 17 (on day 18) of therapy in those who are treated with more than 14 days of clindamycin).